1. Technical Field
This disclosure relates to an image forming apparatus, and more specifically to an image forming apparatus including a recording head for ejecting liquid droplets.
2. Description of the Related Art
Image forming apparatuses are used as printers, facsimile machines, copiers, plotters, or multi-functional devices having two or more of the foregoing capabilities. As one type of image forming apparatus employing a liquid-ejection recording method, an inkjet recording apparatus is known that uses a recording head (liquid-droplet ejection head) for ejecting droplets of ink.
When such a liquid-ejection type image forming apparatus forms an image on a recording medium, the accuracy with which liquid droplets ejected from nozzles are landed on target positions of the recording medium significantly affects image quality. Since a low level of the landing accuracy reduces image quality, the recording head need be positioned at high accuracy.
Meanwhile, if ejection failure occurs in the recording head, it is preferable that the recording head can be easily replaced at a user's site at which the apparatus is used. Even in such a case, the high degree of the positioning accuracy of the recording head must be reproduced at the user's site.
To enhance the positioning accuracy in replacing the recording head, for example, JP-2011-037235-A1 proposes an image forming apparatus including a head holder mounting liquid ejection heads and a carriage removably mounting the head holder. The head holder has positioning portions to contact positioning references in both the carriage scanning direction and the sheet conveyance direction, and the positioning portions serve as positioning references relative to the head holder of liquid ejection head.
However, for the image forming apparatus disclosed in JP-2011-037235-A1, the carriage of the head holder is positioned by positioning faces and pins, thus resulting in a complex configuration. In particular, in a case where the image forming apparatus has multiple head holders, the positioning portions need be provided for the respective head holders. Such a configuration makes it difficult to position the head holders relative to each other, thus hampering easy replacement of the recording head.